1. Field of the Invention
The present invention relates to a power semiconductor device, and more particularly, to a power semiconductor device having an electrode structure for increasing a breakdown voltage by achieving an equipotential state in an electrode contact area and also for achieving a high withstand voltage.
2. Description of the Related Art
Conventionally, a power semiconductor device is made of silicon. However, since silicon has a limit in terms of physical properties, a power semiconductor device using a gallium nitride (GaN)-based material is being newly developed. The GaN-based material has an energy gap that is almost 3 times greater than an energy gap of silicon. Also, the GaN-based material has improved properties such as, high thermal and chemical stability, high electron saturation velocity, and the like. Therefore, the GaN-based material is applicable to not only an optical device but also an electronic device for achieving high frequency and high output.
Electronic devices including the GaN-based material have a high breakdown voltage, high maximum current density, and high operational stability and high heat conductivity at a high temperature. In particular, electronic devices having a hetero junction structure of aluminum gallium nitride (AlGaN) and GaN has high band discontinuity at a junction interface. Thus, such an electronic device may free high density electrons and increase electron mobility.
Due to the foregoing physical property, the electronic device including the GaN-based material may be applied as a power semiconductor device. For this purpose, the power semiconductor device needs to maintain a high withstand voltage without reaching the breakdown voltage even under a high voltage. However, it is difficult for the power semiconductor device including the GaN-based material to endure withstand voltage due to bulk defects, surface defects, and the like.